The present invention relates to an oxygen sensor with an electronic control unit in a car to detect the amount of oxygen in exhaust gas, and more particularly to an improved structure of oxygen sensor, which dissipates heat efficiently, and has means to absorb shocks during its operation.
A car is generally equipped with an oxygen sensor, which detects the amount of oxygen in exhaust gas, and produces a voltage signal indicative of the amount of oxygen detected. The voltage signal from the oxygen sensor is provided to an electronic control unit in the car for analysis, enabling the electronic control unit to adjust the air/fuel ratio automatically. A conventional oxygen sensor is generally comprised of a metal housing, a spring mounted inside the housing, a cylindrical ceramic holder supported on the spring inside the housing, a probe installed in the cylindrical ceramic holder inside the housing to detect the amount of oxygen in exhaust gas from the car and to produce a voltage signal indicative of the amount of oxygen detected, and a terminal connected to the probe and extended out of the housing for transmitting the voltage signal from the probe to the electronic control unit in the car. The spring is provided to absorb shocks only, and not used for signal transmission. Further, because the cylindrical ceramic holder is a solid member, it consumes much material, and provides no space for quick dissipation of heat.
It is one object of the present invention to provide an oxygen sensor, which has a heat dissipation space on the inside for quick dissipation of heat. It is another object of the present invention to provide an oxygen sensor, which uses a metal compression spring to transmit signal, and to absorb shocks when transmitting signal. According to the present invention, the oxygen sensor comprises a metal housing formed of a front cap, a rear cap and an intermediate barrel and secured in shape by a lock nut, a probe mounted in the metal housing to detect of amount of oxygen in exhaust gas from the car and to produce a voltage signal indicative of the amount of oxygen detected, a terminal, which transmits the voltage signal from said probe to the electronic control unit in the car, a water sealing plug fastened to the rear cap and stopped against the intermediate barrel, a first ceramic holder element and a second ceramic holder element respectively mounted inside the intermediate barrel, an electrode washer connected between the first ceramic holder element and the probe, a metal compression spring mounted inside the intermediate barrel to push he ceramic holder elements apart, the metal compression spring having a top end stopped at the electrode washer against the probe and a bottom end extended out of the second ceramic holder element and the water sealing plug, and a lead-out wire connected to the bottom end of the metal compression spring for transmission of the voltage signal from the probe to the electronic control unit in the car. Because the metal compression spring forces the ceramic holder elements apart, a space is left between the ceramic holder elements for quick dissipation of heat.